Scale-dependent emission characteristics of NH3, aldehydes, and nitrosamines from a monoethanolamine-based CO2 capture system in a liquefied natural gas-fired power plant

Hazardous emissions from an MEA-based CO 2 absorption process were investigated through laboratory-scale experiments and field measurements. NH 3 emissions exhibited comparable concentration trends in both systems, indicating that laboratory-scale experiments can reasonably reproduce NH 3 emission behavior under field conditions. Aldehyde emissions were dominated by formaldehyde and acetaldehyde in both systems. In the demonstration plant, the formaldehyde concentration (0.03 ppm) was lower than that in the laboratory-scale system (0.13 ppm), whereas the acetaldehyde concentration (0.17 ppm) was slightly higher than that in the laboratory-scale system (0.11 ppm). Differences in aldehyde speciation between two systems were attributed to gas–liquid interactions and hydration effects in the demonstration plant. In contrast, nitrosamine emissions were scale-dependent. Although overall concentration levels were comparable, six nitrosamine species were detected in the laboratory-scale experiments, whereas only two species were detected in the demonstration plant. N -nitrosomethylethylamine (NMEA), which was the dominant nitrosamine species detected in the laboratory-scale experiments, was not detected in the demonstration plant, highlighting scale-dependent differences in nitrosamine formation and emission behavior. These results demonstrate that laboratory-scale experiments are useful for understanding general trends of NH 3 and aldehyde emissions from MEA-based CO 2 capture systems in LNG-fired power plants. However, nitrosamine speciation cannot be directly extrapolated from laboratory-scale experiments.